Question concerning DRM in PDFs (have things changed since 2007?)

This may have been asked before - my quick search showed 2007 - which is now 5 years ago, so I'm sorry if things haven't changed - but better to be safe than sorry!
I wish to buy "android programming (2nd edition - 2012)", but want to be able to read it on many devices (android/linux laptop) so I was planning to grab it in PDF format.
Can someone tell me if there is now DRM restrictions on the PDFs you sell, and if so what restrictions are there?

We do not apply DRM on any of our ebook or video files. As we state on our ebooks information page, all our ebooks are sold DRM-free. You have lifetime access to the files. You get them in multiple formats, free updates, and can use them on as many devices as you desire.